I've said it before, and I'll say it again - No matter what the issues are, no matter who has the most impressive bona fides - the next and every President of the United States will be elected based on the personality he or she exudes. This is why George H.W. Bush beat Mike Dukakis, and also the reason his son beat John F.-ing Kerry. Would you want to be stuck next to either of those Dems on a cross-country bus ride?
The personality factor is the reason why it has become a standard practice now for all of the candidates to appear on Leno and Letterman... Daily Show and Colbert... and it's a big reason why I think ultimately that Hillary Clinton is in trouble. She has had her moments on the comedy circuit, but I don't think she sells it nearly as well as John McCain or Barack Obama.
Interestingly enough, I have seen McCain give policy speeches before, and he can be like watching paint dry. But he is also known for having a great sense of humor... As for Obama, he took his turn on Letterman last night, handling the Top 10 list chores from the home office, and I think he acquitted himself well:
Now, by way of disclaimer... I may be underestimating Hillary Clinton, because I'm a man and she does not do particularly well with men. But considering we're the gender that has kept the Simpsons on the air... that we're also responsible for every one of the 30 or so Police Academy movies in existence... and that we make up nearly half of the available voting pool out there, Hillary better start getting her funny bone on!